This invention relates to a clamp device for transferring a construction or building material, and more particularly to a clamp device which is adapted to be mounted through any suitable means on an arm of a civil engineering machine such as a hydraulic shovel or the like; a bracket attached to the arm or any other attachment attached to the arm such as a bucket; a clamper or the like to transfer a construction or building material such as a U-shaped gutter; a block; or a Hume pipe or the like to a desired target location while holding or clamping it.
In general, work on a construction or building material (hereinafter referred to as "construction material") such as a U-shaped gutter or the like usually involves arrangement or storage of the construction material; loading and unloading of the construction material with respect to a truck or the like in a manufacturing factory; and a constructor. This work is generally carried out manually. However, it is very hard or substantially impossible to manually handle a construction material which weighs between 500 to 1000 kg such as a large-sized U-shaped gutter or the like. Therefore, a system which uses any convenient means such as a hook would aid in the handling of the construction material. Typically, a wire and a clamp is employed for handling and transferring of the construction material.
Such a handling and transferring system as described above, as shown in FIG. 8, includes a hook 11 which is fixedly mounted by welding on any attachment, such as a bucket 14, connected to an arm 1 of a hydraulic shovel. A wire 13, held at a proximal end thereof on the hook 11, has a clamp 12 mounted on a distal end thereof. The clamp 12 is actuated in association with vertical movement of arm 1, to thereby transferring a construction material 10 while suspending and automatically clamping it.
More specifically, initially, a worker manually operates clamp 12, keeping clamp 12 open so as to permit clamp 12 to get astride construction material 10. Then arm 1 is raised, so that wire 13 is stretched to close clamp 12, resulting in the clamp 12 holding construction material 10. The more construction material 10 weighs, the more clamp 12 is pulled upwardly, through wire 13, to firmly hold construction material 10. Thus, the system permits construction material 10 to be positively transferred to any desired place irrespective of the weight of construction material 10.
The conventional handling and transferring system smoothly accomplishes a normal operation of satisfactorily actuating arm 1 to gradually stretch wire 13 to increase a holding force of clamp 12. This is because of wire 13. However, excessive or violent actuation of arm 1 or sudden inclination or falling of construction material 10, due to unbalanced clamping of construction material 10 by clamp 12, causes the stretching of wire 13 to be suddenly varied. This results in the clamping force of clamp 12 being suddenly decreased or a large magnitude of the force being accidentally applied to hook 11, wire 13 and/or clamp 12. This often causes releasing of construction material 10 from clamp 12; cutting of wire 13; and damage to hook 11 or the like, which, in turn, may lead to serious trouble or accident.
Therefore, it would be desirable to develop a novel and improved device which is capable of eliminating the above-described disadvantages encountered with conventional handling and transferring systems.